The present invention is in the field of digital computers and their related peripherals. In particular, it relates to PCMCIA cards and their insertion into and ejection from computing devices.
Portable digital computers comprise one of the fastest growing segments of the computer industry. Users of portable computers make many mutually contradictory demands on the designers of such machines. Small size and light weight are critical, but users still demand that their portable machines provide them with all or nearly all of the capabilities of their home- or office-bound computer. Unfortunately, the permanent incorporation of devices such as floppy disk drives, modems, extra memory and others to provide the capabilities that the user demands simultaneously increases the computer's weight and often its size.
Relatively recently, small removable devices have become available to designers of portable computers, which devices allow the addition of particular features for whatever period of time that the user needs them, but which can be easily removed whenever these capabilities are no longer desired. At present such cards include flash memory cards, modem cards, hard disk drives and many other similar devices. The size of such cards and their electrical interface has been agreed upon by the Personal Computer Memory Card International Association ("PCMCIA") and the cards are generically referred to in the industry as PCMCIA cards. For purposes of this application, such PCMCIA cards will be referenced as "cards" and the entire class of devices in which they can be used will be referenced as "computers". No limitations regarding the functions of such cards or their use in any type of device should be inferred therefrom.
As the availability and use of these cards has increased, many different mechanisms have been used for both housing the cards while they are inserted in the computer and for ejecting them from the computer. As a result of cost and size considerations, these card housings and ejection mechanisms are usually mechanical, having no motor to assist the operation of the device.
One such housing and ejection mechanism is illustrated in co-pending patent application Ser. No. 08/023,262, filed Feb. 23, 1993, entitled "Ejection Mechanism For Electronic Smart Cards" and assigned to Apple Computer, Inc. That application is incorporated herein for all purposes. The mechanism described therein utilizes a slide fitting which is coupled to a pair of lever arms. Movement of the slide pivots the lever arms, which in turn apply force to the rear of the card, removing it from its electrical connector and pushing it far enough outside the housing so that the user can easily grasp and remove it from the computer. Although the mechanism functions reasonably well, it requires a relatively long travel path for the slide. Additionally, there is no ability to eject the card without the user providing the necessary ejection force.
Other known housings and ejection mechanisms operate on the same principles as those described in the incorporated reference. Various levers and slides are used to apply sufficient mechanical force to the rear of the card to remove it from its connector and eject the card from the computer. In one, in order to generate sufficient force without requiring that the eject pushbutton travel very far, a cam is located at the end of the pushbutton's slide. Although this creates a smaller and more compact ejection mechanism, it still requires that the user provide all the force necessary to eject the card at the time of the card's ejection. Even with the cam, the pushbutton slide extends further beyond the card housing than is desirable.
Although at least one manufacturer of card housings and ejection mechanisms has thought to provide springs to assist the ejection process, the resultant mechanism has several important disadvantages. As two springs are located at the rear of the card housing, the springs being compressed and latched as cards are fully inserted into the housing, a large amount of force is needed to compress the springs. Generally, a card requires 9 lbs. of force to remove it from its connector. Therefore, as the housings are generally constructed to house up to two cards at a time, two 9 lb. springs are needed, which requires that the user insert the cards with 18 lbs. of force. This amount of force is generally unacceptable for a typical user. Once released, this ejection mechanism can also apply too much force to the card, causing it to leave the housing completely upon ejection.
Known mechanisms have to date failed to provide a card housing and ejection mechanism which does not require a great deal of force to insert cards into it, which can eject cards smoothly and easily, without the user providing the mechanical force for the ejection, and which can respond to an internal, computer generated command to eject the card. A housing for this ejection mechanism which can hold the cards in a very compact package without a pushbutton extending from the housing and without the cards themselves extending from the housing would also be very desirable.